A motor control method, device and motor system based on current reconstruction

Abstract

The present invention relates to the field of motor technology, and discloses a motor control method, device and motor system based on current reconstruction, wherein the method comprises obtaining the A-phase current, A-phase and B-phase voltages, and the electrical angle of the rotor of a permanent magnet synchronous motor; reconstructing the B-phase current according to the A-phase current and the rotor electrical angle, and converting the A-phase and B-phase currents and voltages into feedback currents and feedback voltages in a stationary coordinate system respectively; determining the current estimation value at the next moment according to the current estimation value, feedback voltage and back-EMF in the stationary coordinate system at the current moment; the back-EMF at the current moment is determined according to the feedback back-EMF at the current moment and the back-EMF compensation amount, and the back-EMF compensation amount is determined according to the error between the current estimation value and the feedback current. The present invention determines the compensation amount for dynamically adjusting the back-EMF by reconstructing the current and the estimated current, and has high control accuracy, low cost, easy implementation and wide application range for the motor.

Description

Technical Field

[0001] The present invention relates to the field of motor technology, and in particular to a motor control method, device and motor system based on current reconstruction. Background Art

[0002] In traditional three-phase permanent magnet synchronous motor control, current sampling methods include single-resistor sampling, dual-resistor sampling, and triple-resistor sampling. Dual-resistor sampling involves placing the sampling resistors on any two phases at the low end of the three-phase inverter bridge phase line. This requires a sufficient sampling window and limits the final PWM duty cycle. Three-resistor sampling involves placing the sampling resistors on the low end of the three-phase inverter bridge phase line. This requires three amplification sampling circuits and an MCU with three ADC modules capable of simultaneous conversion, resulting in high hardware costs. Single-resistor sampling involves placing the sampling resistors on the bus current and reconstructing the phase currents to estimate the currents of the other two phases. This method is low-cost but suffers from phase current sampling dead zones and phase current reconstruction failures at low speeds.

[0003] To address this issue, Chinese patent application number 2020113804302 discloses a single-current sensor control method for a permanent magnet synchronous motor based on current phase shifting. This method estimates the currents of the other two phases using the current of one phase based on motor parameters and replaces the actual values ​​of the other two phases, thereby improving the robustness and reliability of motor control. However, this algorithm has at least the following shortcomings:

[0004] (1) The algorithm is relatively complex and depends on many motor parameters. The introduction of multiple parameters increases the system error accordingly.

[0005] (2) This method calculates the reference values ​​of the currents of the other two phases based on the phase and amplitude of one phase current. The current feedback value is calculated based on the voltage and motor parameters. The current calculation value is not dynamically corrected. When the motor parameters deviate or the actual voltage and current collected are subject to noise interference, problems such as inaccurate calculation and reduced control accuracy may occur.

[0006] The disclosure of the above background technology content is only used to assist in understanding the inventive concept and technical solution of the present invention. It does not necessarily belong to the prior art of the present application, nor does it necessarily provide technical guidance. In the absence of clear evidence that the above content has been disclosed before the filing date of the present application, the above background technology should not be used to evaluate the novelty and creativity of the present application. Summary of the Invention

[0007] The purpose of the present invention is to provide a motor control method, device and motor system based on current reconstruction. The present invention determines the compensation amount for dynamically adjusting the back electromotive force by reconstructing the current and estimating the current, and has high control accuracy, low cost, easy implementation and wide application range for the permanent magnet synchronous motor.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A motor control method based on current reconstruction includes the following steps:

[0010] Get k Phase A current of the permanent magnet synchronous motor at time i a ( k ), Phase A voltage V a ( k ), B phase voltage V b ( k ) and the electrical angle of the rotor i ( k );

[0011] According to the A phase current i a ( k ) and rotor electrical angle i ( k ) Reconstruction of phase B current i b_rec ( k );

[0012] The A phase current i a ( k ) and B-phase current i b_rec ( k ) is converted to a stationary coordinate system α 、 β Shaft current i α ( k ), i β ( k ) and acts as feedback current, and the voltage V a ( k ), V b ( k ) is converted to a stationary coordinate system α 、 β Shaft voltage V α ( k ), V β ( k ) and serves as feedback voltage;

[0013] according to k Estimated current value at time 、 , k Estimated current value at time 、 Obtained from the previous moment, the feedback voltage V α ( k ), V β ( k ) and the stationary coordinate system α 、 β Axis back EMF and Sure k The stationary coordinate system at time +1 α 、 β Estimated axis current 、 ;in, k Back EMF at the moment and Obtain it in the following ways:

[0014] according to k Estimated current value at time 、 and k Feedback current at moment -1 i α ( k -1) i β ( k -1) Confirm k Back EMF compensation amount at time △ E α ( k ) and △ E β ( k ),in, ,

[0015] , F is the adjustment coefficient;

[0016] Get k Time-stationary coordinate system α 、 β Feedback back EMF of the axis E α ( k ), E β ( k ),according to k Feedback back EMF at the moment E α ( k ), E β (k ) and back EMF compensation △ E α ( k ) and △ E β ( k )Sure k Back EMF at the moment and .

[0017] Furthermore, any one of the above technical solutions or a combination of multiple technical solutions further includes converting the current estimated value 、 Converted to dynamic coordinate system d Shaft current component i d and q Shaft current component i q , d Shaft current component i d and q Shaft current component i q Configured as the input to the feedback control of the field-oriented control current loop.

[0018] Furthermore, based on any one of the above technical solutions or a combination of multiple technical solutions, the control of the permanent magnet synchronous motor further includes speed loop feedback control, including:

[0019] Determined by real-time acquisition of the rotor electrical angle k The electrical angular velocity of the rotor at the moment oh e ( k );

[0020] According to the rotor k Electrical angular velocity at the moment oh e ( k ) and target electrical angular velocity oh ref Determine the speed compensation △ oh e ( k ),△ oh e ( k )= oh ref -oh e ( k );

[0021] Using the rotor speed error △ oh e ( k) controls and adjusts the current rotor speed control quantity to make the rotor speed the target speed.

[0022] Furthermore, based on any one of the above technical solutions or a combination of multiple technical solutions, k +1 time stationary coordinate system α 、 β Estimated axis current 、 Calculated by the following formula:

[0023] ,

[0024] in, L is the stator inductance of the permanent magnet synchronous motor, R is the stator resistance of the permanent magnet synchronous motor, T is the sampling period.

[0025] Furthermore, based on any one of the above technical solutions or a combination of multiple technical solutions, k Back EMF at the moment and Calculated by the following formula:

[0026]

[0027] Furthermore, based on any one of the above technical solutions or a combination of multiple technical solutions, k The coordinate system at rest α 、 β Axis feedback back EMF E α ( k ), E β ( k ) is calculated using the following formula:

[0028] ;

[0029] in, is the permanent magnet flux.

[0030] Furthermore, based on any one of the above technical solutions or a combination of multiple technical solutions, k The electrical angular velocity of the rotor of the permanent magnet synchronous motor at the moment oh e ( k ) can be obtained by:

[0031] oh e ( k )=[ i ( k )- i (k -1)] / T ω ,in, i ( k -1) k -1 moment the rotor electrical angle of the permanent magnet synchronous motor, T ω Calculate the period for electrical angular velocity.

[0032] Furthermore, according to any one of the above-mentioned technical solutions or a combination of multiple technical solutions, according to the A phase current i a ( k ) and rotor electrical angle i ( k ) Reconstruction of phase B current i b_rec ( k ), including the following steps:

[0033] according to k Phase A current of the permanent magnet synchronous motor at time i a ( k ) and the rotor electrical angle i ( k ) Calculate the amplitude of the three-phase current of the permanent magnet synchronous motor I s ( k ), I s ( k ) is calculated as:

[0034] ,

[0035] in, I s ( k -1) is the three-phase current amplitude of the previous control cycle;

[0036] Calculate the phase B current i b_rec ( k ), and its calculation formula is i b_rec ( k )= I s ( k ) cos ( i ( k )-π / 6).

[0037] Furthermore, according to any one of the above technical solutions or a combination of multiple technical solutions, the Clark transformation module is used to transform the A phase current i a (k ) and B-phase current i b_rec ( k ) is converted to a stationary coordinate system α 、 β Shaft current i α ( k ), current i β ( k ); or, use the following formula to convert the phase A current i a ( k ) and B-phase current i b_rec ( k ) is converted to a stationary coordinate system α 、 β Shaft current i α ( k ), current i β ( k ):

[0038] i α ( k )= i a ( k );

[0039] .

[0040] Furthermore, according to any one of the above technical solutions or a combination of multiple technical solutions, the voltage is converted into V a ( k ), V b ( k ) is converted to a stationary coordinate system α 、 β Shaft voltage V α ( k ), V β ( k ); or, convert the voltage V a ( k ), V b ( k ) is converted to a stationary coordinate system α 、 β Shaft voltage V α ( k), V β ( k ):

[0041] V α ( k )= V a ( k );

[0042] .

[0043] According to another aspect of the present invention, the present invention provides a motor control device based on current reconstruction, comprising a current detection module, a voltage detection module, an electrical angle detection module, a phase current amplitude calculation module, a current reconstruction module, a Clark transformation module, a current observer, a speed calculation module, and a motor control module;

[0044] The current detection module is configured to detect the first phase current of the permanent magnet synchronous motor in real time and output it to the phase current amplitude calculation module and the Clark transformation module, where the first phase is any one of the three phases of the permanent magnet synchronous motor;

[0045] The voltage detection module is configured to detect the first phase voltage and the second phase voltage of the permanent magnet synchronous motor in real time and output them to the Clark conversion module;

[0046] The electrical angle detection module is configured to detect the electrical angle of the rotor of the permanent magnet synchronous motor in real time and output it to the current reconstruction module and the speed calculation module;

[0047] The phase current amplitude calculation module is configured to calculate the amplitudes of the three-phase currents according to the current phase current detection values ​​and output them to the current reconstruction module;

[0048] The current reconstruction module is configured to reconstruct the second phase current of the permanent magnet synchronous motor according to the current amplitude of the three-phase current and the electrical angle of the rotor and output the reconstructed current to the Clark transformation module;

[0049] The Clark transformation module is configured to transform the current first phase current and second phase current into the stationary coordinate system. α Shaft current and β The axis current is used as the feedback current and the first phase voltage and the second phase voltage are converted into the stationary coordinate system. α Shaft voltage and β The shaft voltage is used as feedback voltage;

[0050] The speed calculation module is configured to calculate the electrical angular velocity of the rotor at the current moment according to the rotor electrical angle at the current moment and the rotor electrical angle at the previous moment and output the calculated electrical angular velocity to the current observer;

[0051] The current observer is configured to α 、 β The current estimate of the axis, the feedback voltage and the back EMF determine the next moment α 、 β The estimated current value of the axis, and the current value of the α 、 β The error between the estimated current value of the axis and the feedback current at the current moment determines the back EMF at the next moment;

[0052] The motor control module is configured to control the permanent magnet synchronous motor according to an α-axis current estimation value and a β-axis current estimation value at a current moment.

[0053] Furthermore, any one of the above technical solutions or a combination of multiple technical solutions further includes a Park conversion module, wherein the input end of the Park conversion module is electrically connected to the output end of the current observer, the output end of the Park conversion module is electrically connected to the input end of the motor control module, and the Park conversion module is configured to convert the compensated current at the next moment into the current observer. α The shaft current estimate and β The estimated shaft current is converted to the dynamic coordinate system d The shaft current components and q The shaft current component is output to the motor control module;

[0054] The motor control module is configured to receive d The shaft current components and q shaft current component and control d The axis target current component is zero and the control q The permanent magnet synchronous motor is controlled by taking the shaft current component as the target value.

[0055] Furthermore, based on any one of the technical solutions or a combination of multiple technical solutions described above, the motor control module is also configured to receive the electrical angular velocity of the rotor output by the speed calculation module, and control the electrical angular velocity of the rotor of the permanent magnet synchronous motor according to the target electrical angular velocity of the rotor and the electrical angular velocity of the rotor at the current moment.

[0056] According to another aspect of the present invention, the present invention provides a motor system, including a permanent magnet synchronous motor and a motor control device as described in any one of the above technical solutions or a combination of multiple technical solutions, wherein the motor control device is configured to control the working state of the permanent magnet synchronous motor in real time.

[0057] Furthermore, based on any one of the technical solutions or the combination of multiple technical solutions described above, the motor control device is configured to control the working state of the permanent magnet synchronous motor in real time according to the motor control method based on current reconstruction as described in any one of the technical solutions or the combination of multiple technical solutions.

[0058] The beneficial effects brought about by the technical solution provided by the present invention are as follows:

[0059] a. The present invention reduces the number of hardware current sampling circuits by collecting only one phase current. The measured current collected by the normally functioning one-phase current collection circuit is used to reconstruct one of the other two phase currents. The measured phase current and the reconstructed phase current of the one phase are used as feedback currents. The back EMF is dynamically adjusted based on the error between the current estimate and the feedback current, and is used to calculate the current estimate at the next moment. This improves the accuracy and reliability of the current estimate, enabling accurate closed-loop control of the motor current loop. The current estimate leads the collected feedback current by one control cycle, resulting in a fast current control response. Furthermore, the current and estimated currents are reconstructed by software, resulting in low cost, easy implementation, and a wide range of applications.

[0060] b. The motor control method based on current reconstruction provided by the present invention is applicable to the case where only one phase current sampling circuit is normal and the other phase current sampling circuits are faulty, and can be applied as a fault-tolerant method in motor control based on two-phase current sampling or three-phase current sampling;

[0061] c. The present invention also includes a closed-loop control of the dynamic current loop of the permanent magnet synchronous motor, which determines the dynamic coordinate system according to the estimated value of the two-phase current at the next moment of the stationary coordinate system. d The shaft current components and q Shaft current component, d The shaft current components and q The shaft current component is used as the feedback current of the current loop to realize the field-oriented control of the permanent magnet synchronous motor, which can further improve the accuracy and reliability of the motor control.

[0062] d. The present invention determines a rotor speed compensation based on the target rotor speed and the current rotor speed and uses it for feedback control of the speed loop, further improving the accuracy and reliability of motor control. The motor control method proposed in the present invention dynamically adjusts the motor's current loop and speed loop in real time. It relies on few motor parameters, has a simple algorithm, and responds quickly, effectively reducing system errors and improving motor control accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0064] Figure 1 A module schematic diagram of a permanent magnet synchronous motor control device provided by an exemplary embodiment of the present invention;

[0065] Figure 2 A block diagram of a signal sampling principle of a permanent magnet synchronous motor provided by an exemplary embodiment of the present invention;

[0066] Figure 3 A flowchart of a permanent magnet synchronous motor control method provided by an exemplary embodiment of the present invention;

[0067] Figure 4 A spatial relationship diagram of a stationary coordinate system and a dynamic coordinate system provided for an exemplary embodiment of the present invention;

[0068] Figure 5 An exemplary embodiment of the present invention provides a method for controlling the three-phase current vectors. d The spatial relationship diagram of the stationary coordinate system and the dynamic coordinate system when the axis projection is 0;

[0069] Figure 6 A block diagram of a current observer according to an exemplary embodiment of the present invention;

[0070] Figure 7 A diagram showing the relationship between current sampling and rotor angle reading and SVPWM modulated switching waveforms provided for an exemplary embodiment of the present invention;

[0071] Figure 8 A phase current is provided for an exemplary embodiment of the present invention. i a and three-phase current amplitude I s Simulation result interface diagram;

[0072] Figure 9 An interface diagram of simulation results comparing the reconstructed B-phase current and the actual B-phase current provided for an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0073] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0074] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, apparatus, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0075] In one embodiment of the present invention, a motor control method based on current reconstruction is provided. Figure 1 to Figure 3 , including the following steps:

[0076] Real-time acquisition of the permanent magnet synchronous motor's A-phase current, A-phase and B-phase voltages, and rotor electrical angle to obtain k Phase A current of the permanent magnet synchronous motor at time i a ( k ), Phase A voltage V a ( k ), B phase voltage V b ( k ), rotor electrical angle i ( k ) and the electrical angular velocity of the rotor oh e ( k );

[0077] According to the A phase current i a ( k ) and rotor electrical angle i ( k ) Reconstruction of phase B current i b_rec ( k );

[0078] The A phase current i a ( k ) and B-phase current i b_rec ( k ) is converted to a stationary coordinate system α 、 β Shaft current i α ( k ), i β ( k ) and acts as feedback current, and the voltage V a ( k ), V b ( k ) is converted to a stationary coordinate system α 、 β Shaft voltage V α ( k ), V β ( k ) and serves as feedback voltage;

[0079] according to k Estimated current value at time 、 , feedback voltage V α ( k ), V β ( k ) and the stationary coordinate system α 、 β Axis back EMF and Sure k The stationary coordinate system at time +1 α 、 β Estimated axis current 、 ;

[0080] in, k Back EMF at the moment and Obtain it through the following methods:

[0081] according to k Estimated current value at time 、 and k Feedback current at moment -1 i α ( k -1) iβ ( k -1) Confirm k Back EMF compensation amount at time △ E α ( k ) and △ E β ( k ),in, ,

[0082] , F is the adjustment coefficient;

[0083] Get k Time-stationary coordinate system α 、 β Feedback back EMF of the axis E α ( k ), E β ( k ),according to k Feedback back EMF at the moment E α ( k ), E β ( k ) and back EMF compensation △ E α ( k ) and △ E β ( k )Sure k Back EMF at the moment and .

[0084] The motor control method based on current reconstruction provided by the present invention only needs to collect one-phase current, two-phase voltage and the electrical angle of the motor rotor, reconstruct one of the other two-phase currents based on the one-phase current, use the two-phase current of the stationary coordinate system as the feedback current, and use the two-phase voltage of the stationary coordinate system as the feedback voltage. The current estimate value at the previous moment is determined by using the current estimate value, feedback voltage and the electrical angular velocity of the motor. Unlike the existing technology that directly estimates the current based on the feedback current and other related parameters, the present application introduces the compensated back electromotive force to more accurately obtain the current estimate value at the next moment. Figure 6Based on the current estimate and feedback current at the current moment, the back-EMF compensation amount for the next moment is determined. A corrected back-EMF, or compensated back-EMF, is obtained at each moment. This allows for dynamic back-EMF adjustment, ensuring the accuracy and reliability of the current estimate and enabling accurate closed-loop control of the motor. Software-based current and estimated current reconstruction is low-cost, easy to implement, and widely applicable. Furthermore, this method can be applied when only one phase current acquisition circuit is functioning properly while the other phase current sampling circuits are faulty, thus serving as a software fault-tolerance mechanism.

[0085] In order to further improve the control accuracy of permanent magnet synchronous motor, see Figure 1 and Figure 3 ,This method performs the following dynamic control operations on the current loop and speed loop of the permanent magnet synchronous motor.

[0086] like Figure 1 As shown, the motor control method based on current reconstruction also includes converting the current estimation value into a dynamic coordinate system. d Shaft current component i d and q Shaft current component i q , d Shaft current component i d and q Shaft current component i q It is configured as the input of the feedback control of the field oriented control current loop. Specifically, in the process of controlling the motor, d The axis target current component is zero, q The axis target current component is the output of the speed loop controller, d、q Axis target current and d、q The error of the shaft feedback current passes through the current loop controller to achieve magnetic field oriented control of the permanent magnet synchronous motor.

[0087] The dynamic adjustment of the speed loop of the permanent magnet synchronous motor includes the following steps: oh ref and the current rotor speed oh e ( k ) Determine the rotor speed compensation △ oh e ( k ),△ oh e ( k )= oh ref -oh e (k ), the rotor speed compensation is also one of the adjustment quantities of the permanent magnet synchronous motor, and the rotor speed error △ oh e ( k ) controls and adjusts the current rotor speed control quantity to make the rotor speed the target speed.

[0088] The motor control method based on current reconstruction proposed in the present invention takes the A-phase current as a reference, reconstructs the B-phase current, dynamically adjusts the back-electromotive force compensation value to eliminate the error between the current estimation value and the actual current feedback value, determines the current estimation value at the next moment in advance, and adjusts the closed-loop control of the speed loop according to the current electrical angular velocity of the rotor; the two closed loops of the motor's current loop and speed loop are dynamically adjusted in real time, rely on fewer motor parameters, have a simple algorithm, and a fast response speed, effectively reducing system errors and improving the control accuracy of the motor.

[0089] In one embodiment of the present invention, Figure 2 As shown, the A-phase current of the permanent magnet synchronous motor is collected at the current moment. i a ( k ), Phase A voltage V a ( k ), B phase voltage V b ( k ), rotor electrical angle i ( k ). The following specifically describes the method of reconstructing the current of another phase based on the measured phase current of one phase and the calculation of the current estimation value in the stationary coordinate system proposed by the present invention.

[0090] For permanent magnet synchronous motor, its stator phase current i a 、 i b 、 i c is a three-phase balanced sinusoidal current, and the three-phase current synthesizes the phase current vector , They are the magnitudes of the phase currents respectively, and the amplitudes of the three-phase currents are , the three-phase current vectors are 120° apart. Therefore, the following formula is satisfied:

[0091]

[0092] See also Figure 4 and Figure 5 ,in, is the current vector With stationary axis α The angle between is the current vector With dynamic axes d The angle between the axes, i The electrical angle of the motor rotor, i.e. the dynamic coordinate axis d Axis and stationary axis α The angle between the axes.

[0093] When field oriented control is used i d =0 control strategy, the current vector In the dynamic coordinate axis d The component on the axis is i d , dynamic coordinate axis q The component on the axis is i q ,in:

[0094] ;

[0095] because i d =0, then i q = I s ,and .

[0096] Furthermore, the following formula can be derived:

[0097]

[0098] ,when , I s The value from the previous control cycle is adopted.

[0099] Based on the above relationship, the B phase current is reconstructed i b_rec .

[0100] In one embodiment of the present invention, according to the A phase current i a ( k ) and rotor electrical angle i ( k ) Reconstruction of phase B current i b_rec ( k ), including the following steps:

[0101] according to k Phase A current of the permanent magnet synchronous motor at time i a ( k ) and the rotor electrical angle i (k ) Calculate the amplitude of the three-phase current of the permanent magnet synchronous motor I s ( k ), I s ( k ) is calculated as:

[0102] ,

[0103] in, I s ( k -1) is the three-phase current amplitude of the previous control cycle;

[0104] Calculate the phase B current i b_rec ( k ), and its calculation formula is i b_rec ( k )= I s ( k ) cos ( i ( k )-π / 6).

[0105] In this embodiment, the A phase current is calculated by the following formula: i a ( k ) and B-phase current i b_rec ( k ) is converted to a stationary coordinate system α 、 β Shaft current i α ( k ), current i β ( k ), current i α ( k ), current i β ( k )for k Feedback current at the moment:

[0106] i α ( k )= i a ( k );

[0107] .

[0108] The voltage is converted into V a ( k ), V b ( k ) is converted to a stationary coordinate system α 、 β Shaft voltage V α ( k ), V β ( k ),Voltage V α ( k ) and voltage V β ( k )for k Feedback voltage at the moment:

[0109] V α ( k )= V a ( k );

[0110] .

[0111] In this embodiment, the rotor electrical angle of the motor is i Differentiation can be used to obtain the electrical angular velocity of the motor's rotor oh e ,Right now oh e = dth / dt ,in, t For time. Therefore, k The electrical angular velocity of the rotor of the permanent magnet synchronous motor at the moment oh e ( k ) is calculated as: oh e ( k )=[ i ( k )- i ( k -1)] / T ω ,in, i ( k -1) k -1 moment the rotor electrical angle of the permanent magnet synchronous motor, T ωThe electrical angular velocity calculation period is usually a multiple of the sampling period. Specifically, the speed calculation period can be 5-10 times the sampling period. In other embodiments, the electrical angular velocity of the rotor of the permanent magnet synchronous motor is oh e ( k ) can also be obtained through other means such as measurement.

[0112] Calculate the feedback back EMF in the stationary coordinate system based on the rotor electrical angle and rotor electrical angular velocity E α 、 E β , specifically, k The coordinate system at rest α 、 β Feedback back EMF of the axis E α ( k )and E β ( k ) is calculated using the following formula:

[0113] ;

[0114] in, is the permanent magnet flux.

[0115] It should be noted that in this application, the feedback back EMF E α 、 E β Refers to the stationary coordinate system obtained when the back EMF is not compensated α 、 β The back electromotive force of the axis can be calculated using the above formula in this application, or obtained through other calculation formulas or a back electromotive force observer.

[0116] In the prior art, the currents of other phases are directly reconstructed based on one phase current, and the current estimation value is further calculated. The current estimation value may have a large error with the actual feedback current of the motor, which leads to low control accuracy of the motor. In order to more accurately determine the current estimation value and make the current estimation value closer to the actual feedback current, the present application uses the compensated back EMF to calculate the current estimation value. and Calculate the estimated current value at the next moment.

[0117] Specifically, the current estimated value at the current moment of the stationary coordinate system is 、 ,Voltage V α 、 V β , back EMF and , stator inductance L and electronic resistors R The stationary coordinate system at the next moment can be estimated α 、 β Estimated axis current , current estimation value Satisfies the following formula:

[0118] ;

[0119] therefore, k +1 time stationary coordinate system α 、 β Estimated axis current i α ( k +1), i β ( k +1) is calculated using the following formula:

[0120] ,

[0121] in, L is the stator inductance of the permanent magnet synchronous motor, R is the stator resistance of the permanent magnet synchronous motor, T is the sampling period.

[0122] in, k Back EMF at the moment and Calculated by the following formula:

[0123]

[0124] Among them, E α ( k ) and △ E β ( k )yes k -1 moment, the calculation formulas are as follows:

[0125] in, F is the adjustment coefficient.

[0126] It should be noted that the back EMF compensation amount needs to be calculated at each moment. The back EMF compensation amount at the current moment is used to compensate and correct the back EMF at the next moment, and the back EMF at the next moment is used to calculate the current estimation value at the next moment.

[0127] exist k Time calculation kBack EMF compensation amount at time +1△ E α ( k +1) and △ E β ( k +1), △ E α ( k +1) According to k Determined at any moment k Estimated current value at time +1 and k Feedback current at the moment i α ( k ) error determination, △ E β ( k +1) According to k Determined at any moment k Estimated current value at time +1 and k Feedback current at the moment i β ( k ) error determination.

[0128] use k Back EMF compensation amount at time +1△ E α ( k +1) and △ E β ( k +1) Calculation k The back electromotive force and the back electromotive force at the +1 moment are calculated as follows:

[0129]

[0130] in, E α ( k +1) and E β ( k +1) is k +1 moment according to the motor k +1 moment is determined by the electrical angular velocity and electrical angle, k Back EMF at time +1 and Used to determine the current estimate at time k+2.

[0131] By dynamically adjusting the input variables of the back EMF, the error between the current estimation value and the feedback current value based on the current of phase A can be eliminated. That is, the current estimation value obtained in this application is closer to the actual feedback current.

[0132] The estimated current and Input Park conversion module to convert and obtain and output the dynamic coordinate system d Shaft current component i d ( k +1) and q Shaft current component i q ( k +1) as feedback for dynamic regulation of the motor control current loop. Based on this feedback, the voltage vector switching time is calculated using field-oriented control and space vector pulse width modulation (SVPWM). This is then used to load the PWM module output to the three-phase inverter during the next control cycle.

[0133] The present invention estimates the current in a stationary coordinate system, and the current estimation value leads the collected current by one control cycle, so that the current control response is fast; the error between the current estimation value and the actual collected current value is used to dynamically adjust the back electromotive force to ensure the accuracy and reliability of the current estimation value. This method is based on software-based current reconstruction and estimated current, has low application cost, is easy to implement, and has a wide range of application scenarios.

[0134] In one embodiment of the present invention, a motor control device based on current reconstruction is provided, such as Figure 1 As shown, the motor control device includes a current detection module, a voltage detection module, an electrical angle detection module, a phase current amplitude calculation module, a current reconstruction module, a Clark transformation module, a current observer, a Park transformation module, a speed calculation module and a motor control module.

[0135] The current detection module is configured to detect the first-phase current of the permanent magnet synchronous motor in real time and output it to the phase current amplitude calculation module and the Clark transformation module. The first phase is any one of the three phases of the permanent magnet synchronous motor. The voltage detection module is configured to detect the first-phase voltage and the second-phase voltage of the permanent magnet synchronous motor in real time and output them to the Clark transformation module. The electrical angle detection module is configured to detect the electrical angle of the rotor of the permanent magnet synchronous motor in real time and output it to the current reconstruction module and the speed calculation module.

[0136] In a specific embodiment, Figure 2 As shown, the acquisition circuit includes a single-phase current sampling circuit, a two-phase voltage sampling circuit and a motor position sensor installed on the motor controller.

[0137] Optionally, the current sampling circuit adopts a sampling resistor, and the sampling resistor is placed at the low end of the lower bridge arm of any phase of the three-phase inverter. The voltage across the sampling resistor is amplified by the sampling amplifier circuit and input to the ADC sampling port of the single-chip microcomputer MCU. The motor phase voltage is input to the ADC sampling port of the single-chip microcomputer MCU after voltage division by the resistor. The software reads the single-phase current value by reading the ADC register. Of course, in other embodiments, the two-phase current can also be directly collected. The two-phase current measured value is directly used in the motor control that directly collects the two-phase current, and there is no need to estimate the other phase current based on the one-phase current. The A and B phase voltages are collected and input to the ADC sampling port of the single-chip microcomputer after voltage division by the resistor, and the software reads the A and B phase voltages by reading the ADC register.

[0138] Optionally, the motor position sensor installed in the motor controller uses an angle sensor (MPS). The microcontroller (MCU) is connected to the motor position angle sensor (MPS) via an SPI communication line. The MCU reads the rotor electrical angle value detected by the angle sensor (MPS) via SPI communication. The rotor position angle can also be acquired by the position sensor, which can be a magnetoresistive sensor.

[0139] In this embodiment, the closed-loop control principle of the motor is as follows: Figure 1 and Figure 6 As shown, the phase current amplitude calculation module calculates the amplitude of the three-phase current according to the current phase current detection value I s And output to the current reconstruction module. Phase current amplitude of three-phase current I s The calculation method of is as described in the above-mentioned embodiment of the motor control method based on current reconstruction.

[0140] according to k Phase A current of the permanent magnet synchronous motor at time i a ( k ) and the rotor electrical angle i ( k ) Calculate the amplitude of the three-phase current of the permanent magnet synchronous motor I s ( k ), I s ( k ) is calculated as:

[0141] ,

[0142] in, I s ( k -1) is the three-phase current amplitude of the previous control cycle.

[0143] The current reconstruction module reconstructs the second phase current of the permanent magnet synchronous motor according to the current amplitude of the three-phase current and the electrical angle of the rotor and outputs the reconstructed current to the Clark transformation module;

[0144] The Clark transformation module converts the current first phase current i a and the second phase current i b_rec Converted to the stationary coordinate system α Shaft current i α and β Shaft current i β and the first phase voltage V a and the second phase voltage V b Converted to the stationary coordinate system α Shaft voltage V α and β Shaft voltage V β And output to the current observer.

[0145] According to the Clark transformation module in the field oriented control, only two phase currents need to be input to perform Clark transformation. i a and the reconstructed phase current i b_rec As the input of the Clark transformation module, we can get the α Current on the axis i α and β Current on the axis i β .

[0146] In addition, the first phase voltage V a and the second phase voltage V b As the input of the Clark transformation module, we can get the stationary coordinate system α Voltage on the shaft V α and β Voltage on the shaft V β .

[0147] The speed calculation module is configured to calculate the electrical angular velocity of the rotor at the current moment based on the rotor electrical angle at the current moment and the rotor electrical angle at the previous moment and output it to the current observer. The calculation method is specifically as described in the above-mentioned motor control method embodiment based on current reconstruction, and will not be repeated here.

[0148] The current observer is configured to α 、 β Estimated shaft current, α Shaft voltage, β The shaft voltage and back EMF determine the next moment α 、 β The estimated current value of the axis, and the current value of the α 、 β The back electromotive force at the next moment is determined by the error between the current estimation value of the axis and the feedback current at the current moment; wherein the back electromotive force at the current moment is determined according to the feedback back electromotive force at the current moment and the back electromotive force compensation amount obtained at the previous moment, that is, Figure 6 As shown, the current observer outputs the current estimation value and the back EMF compensation amount of the next moment at each moment. The back EMF compensation amount of the next moment is used to compensate for the feedback back EMF of the next moment, and the compensated back EMF of the next moment is used to calculate the current estimation value of the next moment.

[0149] The Park transformation module will α The shaft current estimate and β The estimated shaft current is converted to the dynamic coordinate system d The shaft current components and q axis current component and output it to the motor control module; the motor control module is configured to d The shaft current components and q Shaft current components and target d The shaft current component is zero to compensate for the dynamic current of the permanent magnet synchronous motor, so as to realize closed-loop control of the dynamic current loop of the motor.

[0150] like Figure 1 As shown, the motor control module includes a speed loop controller, a current loop controller, a PARK inverter, a SVWMP module and an inverter circuit which are electrically connected in sequence. The motor control module is configured as follows: d The axis target current component is zero, q The axis target current component is the output of the speed loop controller, d The shaft current components and q The shaft current component serves as the feedback current of the current loop. d、q Axis target current and d、q The error of the shaft feedback current passes through the current loop controller to achieve magnetic field oriented control of the permanent magnet synchronous motor.

[0151] In addition, the motor control module is also configured to receive the electrical angular velocity of the rotor output by the speed calculation module, and control the electrical angular velocity of the rotor of the permanent magnet synchronous motor according to the target electrical angular velocity of the rotor and the electrical angular velocity of the rotor at the current moment, so as to realize closed-loop control of the speed loop of the motor.

[0152] The present invention can effectively improve the reliability and accuracy of motor control by closed-loop controlling both the current loop and the speed loop of the motor.

[0153] In one embodiment of the present invention, the control effect of the motor control method and device based on current reconstruction provided by the present invention on the permanent magnet synchronous motor is verified through simulation. Figure 7 to Figure 9 ,in Figure 7 This is a diagram showing the relationship between current sampling and rotor angle reading and the SVPWM modulated switching waveform in this embodiment; current sampling and motor rotor angle reading are synchronized, and the phase current is collected and the motor rotor position angle is read at the middle position when the lower bridge arm of phase A is opened. Figure 8 The first phase current is A phase current i a and phase current amplitude I s Simulink simulation result diagram and simulation result interface diagram. Figure 9 is the reconstructed value of phase B current of the current observer i b_rec Simulation result interface diagram compared with the actual current of phase B, reconstructed phase current i b_rec Compared with the actual current of phase B in the motor, the amplitude and phase are basically consistent, which is in line with expectations. It can be seen that the motor control method and device based on current reconstruction provided by the present invention have an ideal control effect on the permanent magnet synchronous motor.

[0154] In one embodiment of the present invention, a motor system is provided, comprising a permanent magnet synchronous motor and a motor control device as described in any of the above embodiments, wherein the motor control device is configured to control the operating state of the permanent magnet synchronous motor in real time. The motor control device is configured to control the operating state of the permanent magnet synchronous motor in real time according to the method described in any of the above embodiments of the motor control method based on current reconstruction.

[0155] It should be noted that the above-mentioned motor system, motor control device embodiment based on current reconstruction and motor control method embodiment based on current reconstruction belong to the same inventive concept, and the entire content of the motor control method embodiment based on current reconstruction is incorporated into the motor system and motor control device embodiment based on current reconstruction by reference.

[0156] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0157] The above is only a specific implementation method of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A motor control method based on current reconstruction, characterized in that: The following steps are involved: Get k Phase A current of permanent magnet synchronous motor at time i a ( k ), A phase voltage V a ( k ), B phase voltage V b ( k ) and the electrical angle of the rotor θ ( k ); According to the A phase current i a ( k ) and the rotor electrical angle θ ( k ) Reconstruction of phase B current i b_rec ( k ); The A phase current i a ( k ) and B phase current i b_rec ( k ) is converted to a stationary coordinate system α , β Shaft current i α ( k ), i β ( k ) and as feedback current, and the voltage V a ( k ), V b ( k ) is converted to a stationary coordinate system α , β Shaft voltage V α ( k ), V β ( k ) and used as feedback voltage; according to k Estimated current value at time , , feedback voltage V α ( k ), V β ( k ) and the stationary coordinate system α , β Axis back EMF and Sure k +1 time stationary coordinate system α , β Estimated axis current , ;in, k Back EMF at time and Obtained through: according to k Estimated current value at time , and k Feedback current at -1 moment i α ( k -1) i β ( k -1) OK k Back EMF compensation at time and ,in, , , F is the adjustment coefficient; Get k Time-stationary coordinate system α , β Feedback back EMF of the axis E α ( k ), E β ( k ),according to k Feedback back EMF at the moment E α ( k ), E β ( k ) and back EMF compensation and Sure k Back EMF at time and .

2. The motor control method based on current reconstruction according to claim 1, characterized in that: It also includes the current estimate , Convert to dynamic coordinate system d Shaft current component i d and q Shaft current component i q , d Shaft current component i d and q Shaft current component i q Configured as the input quantity for the feedback control of the field oriented control current loop.

3. The motor control method based on current reconstruction according to claim 1, characterized in that: The control of the permanent magnet synchronous motor also includes speed loop feedback control, including: Determined by real-time acquisition of the rotor electrical angle k The electrical angular velocity of the rotor at the moment ω e ( k ); according to k The electrical angular velocity of the rotor at the moment ω e ( k ) and target electrical angular velocity ω ref Determine the speed compensation amount , ; Using the rotor speed error The current rotor speed control amount is controlled and adjusted to make the rotor speed the target speed.

4. The motor control method based on current reconstruction according to claim 1, characterized in that: k +1 time stationary coordinate system α , β Estimated axis current , Calculated by the following formula: ， in, L is the stator inductance of the permanent magnet synchronous motor, R is the stator resistance of the permanent magnet synchronous motor, T is the sampling period.

5. The motor control method based on current reconstruction according to claim 4, characterized in that: k Back EMF at time and Calculated by the following formula: ， 。 6. The motor control method based on current reconstruction according to claim 5, characterized in that: k The coordinate system of the stationary α , β Axis feedback back EMF E α ( k ), E β ( k ) is calculated by the following formula: ； in, is the permanent magnet flux, ω e ( k )for k The electrical angular velocity of the rotor at time .

7. The motor control method based on current reconstruction according to claim 6, characterized in that: k The electrical angular velocity of the rotor of the permanent magnet synchronous motor at the moment ω e ( k ) can be obtained by: ω e ( k )=[ θ ( k )- θ ( k -1)] / T ω ,in, θ ( k -1) k -1 The rotor electrical angle of the permanent magnet synchronous motor at time, T ω Calculate the period for the electrical angular velocity.

8. The motor control method based on current reconstruction according to claim 1, characterized in that: According to the A phase current i a ( k ) and the rotor electrical angle θ ( k ) Reconstruction of phase B current i b_rec ( k ), including the following steps: according to k Phase A current of permanent magnet synchronous motor at time i a ( k ) and the rotor electrical angle θ ( k ) Calculate the amplitude of the three-phase current of the permanent magnet synchronous motor I s ( k ), I s ( k ) is calculated as: ， in, I s ( k -1) is the three-phase current amplitude of the previous control cycle; Calculate the phase B current i b_rec ( k ), and its calculation formula is i b_rec ( k )= I s ( k ) cos ( θ ( k )-π / 6).

9. The motor control method based on current reconstruction according to claim 1, characterized in that: The A phase current can be calculated by the following formula i a ( k ) and B phase current i b_rec ( k ) is converted to a stationary coordinate system α , β Shaft current i α ( k ), current i β ( k ): i α ( k )= i a ( k )； 。 10. The motor control method based on current reconstruction according to claim 1, characterized in that: The voltage is converted into V a ( k ), V b ( k ) is converted to a stationary coordinate system α , β Shaft voltage V α ( k ), V β ( k ): V α ( k )= V a ( k )； 。 11. A motor control device based on current reconstruction, characterized in that: It includes a current detection module, a voltage detection module, an electrical angle detection module, a phase current amplitude calculation module, a current reconstruction module, a Clark transformation module, a current observer, a speed calculation module and a motor control module; The current detection module is configured to detect the first phase current of the permanent magnet synchronous motor in real time and output it to the phase current amplitude calculation module and the Clark transformation module, wherein the first phase is any one of the three phases of the permanent magnet synchronous motor; The voltage detection module is configured to detect the first phase voltage and the second phase voltage of the permanent magnet synchronous motor in real time and output them to the Clark transformation module; The electrical angle detection module is configured to detect the rotor electrical angle of the permanent magnet synchronous motor in real time and output it to the current reconstruction module and the speed calculation module; The phase current amplitude calculation module is configured to calculate the amplitudes of the three-phase currents according to the current phase current detection values ​​and output them to the current reconstruction module; The current reconstruction module is configured to reconstruct the second phase current of the permanent magnet synchronous motor according to the current amplitude of the three-phase current and the rotor electrical angle and output it to the Clark transformation module; The Clark transformation module is configured to transform the current first phase current and the second phase current into the stationary coordinate system. α Shaft current and β The shaft current is used as the feedback current and the first phase voltage and the second phase voltage are converted into the stationary coordinate system. α Shaft voltage and β The shaft voltage is used as feedback voltage; The speed calculation module is configured to calculate the electrical angular velocity of the rotor at the current moment according to the rotor electrical angle at the current moment and the rotor electrical angle at the previous moment, and output the calculated electrical angular velocity to the current observer; The current observer is configured to α , β The current estimate of the axis, the feedback voltage and the back EMF determine the next moment α , β The estimated current value of the axis, and the α , β The error between the estimated current value of the axis and the feedback current at the current moment determines the back EMF at the next moment; The motor control module is configured to control the permanent magnet synchronous motor according to an α-axis current estimation value and a β-axis current estimation value at a current moment.

12. The motor control device based on current reconstruction according to claim 11, characterized in that: The system further comprises a Park transformation module, wherein the input end of the Park transformation module is electrically connected to the output end of the current observer, the output end of the Park transformation module is electrically connected to the input end of the motor control module, and the Park transformation module is configured to convert the compensated current at the next moment into the current observer. α The shaft current estimate and β The shaft current estimate is converted to the dynamic coordinate system d The shaft current components and q The shaft current component is output to the motor control module; The motor control module is configured to receive d The shaft current components and q shaft current component and controls d The axis target current component is zero and the control q The permanent magnet synchronous motor is controlled with the shaft current component as the target value.

13. The motor control device based on current reconstruction according to claim 11, characterized in that: The motor control module is also configured to receive the electrical angular velocity of the rotor output by the speed calculation module, and control the electrical angular velocity of the rotor of the permanent magnet synchronous motor according to the target electrical angular velocity of the rotor and the electrical angular velocity of the rotor at a current moment.

14. A motor system, characterized in that: It comprises a permanent magnet synchronous motor and a motor control device as described in any one of claims 11 to 13, wherein the motor control device is configured to control the working state of the permanent magnet synchronous motor in real time.

15. The motor system according to claim 14, characterized in that The motor control device is configured to control the working state of the permanent magnet synchronous motor in real time according to the motor control method based on current reconstruction according to any one of claims 1 to 10.

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